Vaccination syringe

ABSTRACT

A replaceable needle assembly is provided for a retractable, prefilled syringe comprising a barrel having a mounting member and a plunger, whereby the retractable needle can be replaced by a user without affecting the retraction mechanism. The replaceable needle assembly comprises a needle fitted to a retractable needle mount and a needle retainer. The needle mount is removably, screw-threadedly mountable to the mounting member of the barrel. The needle retainer comprises a plurality of fingers that releasably engage the retractable needle to thereby prevent inadvertent retraction of the retractable needle before engagement by the plunger. The plunger comprises a plunger seal comprising an outer member and an inner member that engages the needle for spring-driven retraction. At the end of retraction, a lock is formed between the plunger and barrel to prevent re-use of the syringe.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is the U.S. national stage of InternationalPatent Application No. PCT/AU2010/001505, filed Nov. 11, 2010, whichclaims the benefit of U.S. Provisional Patent Application No.61/260,252, filed Nov. 11, 2009, the disclosures of which are hereinincorporated by reference.

FIELD

This invention relates to syringes. More particularly, this inventionrelates to a retractable syringe that includes a replaceable,retractable needle.

BACKGROUND

The practice of sharing syringes without adequate sterilization betweensuccessive users is a major contributor to the transfer of HumanImmunodeficiency Virus (HIV) and Hepatitis with subsequent severerepercussions for the sufferer and at a high cost to society forsupporting and providing medical attention to sufferers. Furtherproblems arise for health professionals administering medicines andvaccines to infected individuals, where accidental needle stick injuryby a used syringe can lead to infection.

In response to this problem, syringes have been developed which eitherprovide a needle sheathing mechanism or a needle retraction mechanism toprevent re-use and/or needle stick injury.

However, many such retractable syringes have fixed needles or highlyspecialized retractable needle assemblies that are not amenable toreplacing needles which have been bent or burred or for allowing a userto select an appropriate needle size.

SUMMARY

The invention is therefore, at least in part, broadly directed to areplaceable needle assembly for a retractable syringe, whereby aretractable needle can be replaced by a user without affecting theretraction mechanism.

The invention is also broadly directed to a barrel suitable for mountingthe replaceable needle assembly.

The invention also broadly provides an improved retraction mechanismcomprising respective elements of the retractable needle assembly and/ora plunger capable of engaging and retracting a retractable needle.

In a first aspect, the invention provides a replaceable needle assemblyfor a retractable syringe comprising a plunger and a barrel having amounting member, said replaceable needle assembly comprising: aretractable needle that is engageable by said plunger; a needle mountthat is removably mountable to the mounting member of the barrel; and aneedle retainer.

In one embodiment the needle mount comprises a male member which isreceivable by a female member of said mounting member.

Preferably, the needle mount comprises a screw-thread which in use isreceived by a complementary screw thread of said mounting member.

In a preferred embodiment, the needle retainer comprises a plurality offingers that engage said retractable needle to prevent inadvertentretraction of said retractable needle.

In a second aspect, the invention provides a barrel for a retractablesyringe, said barrel comprising a mounting member to which is removablymountable a replaceable needle assembly.

In one embodiment, said mounting member comprises a female member thatreceives a male member of a needle mount of said retractable,replaceable needle assembly.

Preferably, the mounting member comprises a screw-thread which in usereceives a complementary screw thread of a needle mount of saidreplaceable needle assembly.

Preferably, the barrel further comprises a needle seal coupled to themounting member.

Preferably, the barrel comprises a releasing member.

In one embodiment, the barrel further comprises a collar.

Preferably, the collar comprises the releasing member.

In a third aspect, the invention provides a plunger for a retractablesyringe comprising a retractable needle, said plunger comprising: abiasing means; a plunger member releasably connected to a control rod; aplunger housing; and a plunger seal mounted to the plunger member;wherein the plunger member, control rod and plunger housing co-operateto maintain said biasing means in an initially energized state prior toretraction.

Suitably, the plunger comprises a needle-engaging portion that iscapable of engaging the retractable needle to facilitate retraction ofthe retractable needle.

In one embodiment, the plunger seal comprises an inner member and anouter member. Preferably, the plunger seal comprises a stop to preventor minimize forward travel of the inner member relative to the outermember. Suitably, according to this embodiment the inner membercomprises the needle-engaging portion.

Preferably, said plunger is arranged so that at the end of depression ofsaid plunger to deliver fluid contents of said retractable syringe, saidcontrol rod disengages from said plunger housing to facilitate a releaseof energy from said biasing means to thereby retract said control rodand said plunger member with a needle coupled thereto.

Preferably, said needle is coupled to said inner member of said seal. Anadvantage of this embodiment is that because the outer member of theseal remains stationary during retraction, the “glide force” required toretract the inner member and coupled needle is relatively reduced.

Suitably, said biasing member is any device which can store energy in areleasable form, such as a spring, elastic or the like.

Preferably, said biasing means is a spring.

In a fourth aspect, the invention provides a retractable syringe kitcomprising the barrel of the second aspect prefilled with fluid contentsand the plunger of the third aspect in combination; and a plurality ofneedle assemblies according to the first aspect.

In one embodiment of the retractable syringe kit, the plurality ofneedle assemblies respectively comprise a 0.5 inch needle, a 1.0 inchneedle and a 1.5 inch needle.

In a fifth aspect, the invention provides a retractable syringecomprising: the replaceable needle assembly of the first aspectremovably mounted to the barrel of the second aspect; and/or the plungerof the third aspect.

In one embodiment, the retractable syringe further comprises a lockformed between said plunger housing and said collar of said barrel whichprevents or hinders removal of the plunger housing from the retractablesyringe after retraction of the retractable needle.

Preferably, the retractable syringe is a prefilled retractable syringe.

In a sixth aspect, the invention provides a method of operating aretractable syringe including the step of removably mounting areplaceable needle assembly to a barrel of a retractable syringeprefilled with fluid contents.

Preferably, the method includes the step of removing a plug from amounting member of the barrel prior to removably mounting thereplaceable needle assembly to the barrel.

In one embodiment, the method includes the step of screw-threadedlymounting a needle mount of the replaceable needle assembly to a mountingmember of the barrel.

In a seventh aspect, the invention provides a method of making apre-filled syringe including the steps of coupling a plunger and a sealin a syringe barrel, wherein the syringe barrel comprises fluidcontents, a plug member mounted thereto or a replaceable needle assemblyof the first aspect mounted thereto.

Throughout this specification, unless otherwise indicated, “comprise”,“comprises” and “comprising” are used inclusively rather thanexclusively, so that a stated integer or group of integers may includeone or more other non-stated integers or groups of integers.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting embodiments of the invention are described herein withreference to the following drawings wherein:

FIG. 1 is a sectional view of an embodiment of a retractable syringe;

FIG. 2 is a sectional view of an embodiment of a plunger;

FIG. 3 is a sectional view of an embodiment of a replaceable needleassembly;

FIG. 4A is a sectional view of an embodiment of a barrel prior toremoval of a plug and FIG. 4B is a sectional view showing mounting of areplaceable needle assembly to a barrel mounting member;

FIG. 5 is a sectional view of a plunger engaging a needle assembly priorto needle retraction;

FIG. 6 is a sectional view showing spring-driven retraction of aplunger, plunger rod and retractable needle; and

FIG. 7 is a sectional view showing an embodiment of a retractablesyringe after retraction of a retractable needle.

DETAILED DESCRIPTION

Referring to FIG. 1, an embodiment of syringe 10 comprises barrel 11 andplunger 20 which is slidably, axially moveable within barrel 11, plunger20 having plunger member 50 and plunger housing 21. Replaceable needleassembly 30 comprises retractable needle 39 that comprises cannula 31and needle body 32 comprising plunger-engaging foot 33, needle mount 36having screw threaded portion 370 and needle retainer 35. Seal 80 ismounted to projection 52 of plunger member 50. Barrel 11 comprisesplunger end 12 at which is located collar 13 comprising release ring 14having rim 141. Barrel 11 also comprises needle end 15 having mountingmember 16 onto which can be mounted replaceable needle assembly 30.Mounting member 16 comprises screw thread 17 and is typically glued orotherwise firmly affixed inside needle end 15 of barrel 11. Needle seal40 is also mounted inside needle end 15 of barrel 11 behind mountingmember 16 (i.e proximal to the user). Sealing base 41 of needle seal 40seals against inside wall 18 of barrel while body 42 is coupled tomounting member 16.

Referring now to FIG. 2, plunger 20 comprises plunger housing 21 withskirt 22 having flange 23 comprising inner circumferential ledge 24.Skirt 22 also comprises step 27 at an end of skirt 22 proximal to auser. Plunger housing 21 further comprises arm 28 having shoulder 29.Control rod 60 is releasably connected to plunger member 50 by way offrangible connection 61. Control rod further comprises shaft 62, button63 which is operable by a user and trigger 64 which comprises notch 65.In this embodiment, the biasing means is spring 70. Before retraction,trigger 64 of control rod 60 engages flange 23 of plunger housing 21 byway of notch 65 releasably engaging inner circumferential ledge 24. Thisretains spring 70 in an initially compressed state, compressed betweeninner shoulder 25 of plunger housing and annular base 51 of plungermember 50. In this context, “initially compressed” means that spring 70is in a compressed (i.e energized) state before use of the retractablesyringe.

Plunger member 50 further comprises projection 52, which in thisembodiment is screw threaded, which is coupled to plunger seal 80.Plunger seal 80 comprises inner member 81 and outer member 82 that arereleasably coupled. Stop 85 is formed between shoulder 86 of innermember 81 and ledge 87 of outer member 82 to minimize or preventunwanted forward travel of inner member 81 relative to outer member 82(i.e towards needle end 15 of barrel 11), particularly when plunger 20is initially inserted into barrel 10. Stop 85 selectively allows axialmovement of inner member 81 relative to outer member 82 towards the userduring retraction, as will be described in more detail hereinafter.Inner member 81 further comprises complementary mating portion 83 forreceiving and engaging foot 33 of needle body 32 and plunger-engagingrecess 84 that is screw-threadedly mounted to projection 52 of plungermember 50. Outer member 82 seals against inside wall 18 of barrel toprevent fluid leaking from fluid space 19. It is also noted that innermember 81 and outer member 82 provide a fluid-tight seal at internalinterface 88. Although not shown, complementary annular ribs and groovescould be added to inner member 81 and outer member 82, or vice versa, tofacilitate the fluid-tight seal.

As shown in FIG. 3, replaceable needle assembly 30 comprises retractableneedle 39 comprising cannula 31, needle body 32 that comprisesplunger-engaging foot 33 and shoulders 34A, 34B, needle retainer 35 andneedle mount 36 having screw threaded “male” portion 370. Needleretainer 35 also comprises fingers 37A, B that respectively bear againstshoulders 34A, 34B of needle body 32 which retain retractable needle 39in needle assembly 30 and prevent inadvertent retraction of retractableneedle 39. This retaining function can withstand up to a 6N force, butnevertheless allow spring-driven retraction of retractable needle 39, aswill be described in more detail hereinafter. An advantage of thisarrangement is that no other structure (e.g. an ejector member) isrequired to release retractable needle 39 from fingers 37A, 37B.Complementary angled faces 38A, B, C and D also assist preventinginadvertent ejection of retractable needle, if for example subjected toa “needle pull” force 39 from needle assembly 30.

Referring now to FIGS. 4A and 4B, syringe 10 is typically providedprefilled with fluid contents, such as a vaccine, although withoutlimitation thereto. As is evident in FIG. 4A, prior to use, plug 90comprising screw-threaded portion 91 has been fitted into complementaryscrew-thread 17 of mounting member 16 at needle end 15 of barrel 11 tothereby seal barrel 11. Plug 90 is then unscrewed as indicated by thearrow and removed by the user so that replaceable needle assembly 30 canbe mounted by way of screw thread 35 in needle mount 36 engagingcomplementary screw thread 17 in mounting member 16. Replaceable needleassembly 30 may be provided with a removable cover (not shown) forcannula 31 and also a screw-threaded cover (not shown) mountable toscrew thread 35 of needle mount 36. Once these covers are removed andthe needle assembly mounted to barrel 11, syringe 10 is ready for use.It will be appreciated that the replaceable needle assembly 30 allows auser to replace a needle that becomes bent or burred. Furthermore, auser may select an appropriate size or gauge needle for delivery.

Referring to FIG. 5, in use plunger 20 is moved axially in the directionof the solid arrow toward needle end 15 of barrel 11 to deliver fluidcontents of syringe 10. At or near the end of plunger 20 depression,complementary mating portion 83 of seal inner 81 receives and snap-lockengages foot 33 of needle body 32. This effectively couples retractableneedle 39 to plunger member 50, as shown in FIG. 5. It will also beappreciated that while this embodiment describes male-female engagementbetween foot 33 and complementary mating portion 83, the reversearrangement is also contemplated.

The sequence of events that occur to facilitate controlled retraction ofretractable needle 39 is as follows.

Continued movement of plunger 20 in the direction of the solid arrow inFIG. 5 is allowed by seal 80 and needle seal 40, which are formed of acompressible material and allow continued movement of plunger housing 21toward needle end 15 of barrel 11 until release ring 14 bears againstarm 64 of control rod 60, thereby moving trigger 64 radially inwardly inthe direction of the arrow in FIG. 5. This disengages notch 65 frominner circumferential ledge 24 which thereby triggers release of controlrod 60 from plunger housing 21. This allows initially compressed spring70 to decompress and forcibly bear against annular base 51 of plungermember 50 to thereby retract plunger member 50 and connected control rod60. Retraction of plunger member 50 occurs with sufficient force todislodge needle body 32 from fingers 37A, B of needle retainer 35. Atthis time, inner member 81 of plunger seal 80 uncouples from outermember 82, moving axially towards the user so that cannula 31 and needlebody 32, which is coupled to inner sealing member 81 mounted to plungermember 50, retracts in the direction of the arrow in FIG. 6 (insideplunger housing 21 which remains stationary relative to barrel 11).

Accordingly, control rod 60 retracts, the rate of which retraction iscontrolled by a user relaxing pressure (such as by way of thumbpressure) against control button 63. As shown in FIG. 7, retraction iscomplete when base 51 of first plunger member 50 abuts step 27 inplunger housing 21 which is stationary during retraction of plungermember 50 and control rod 60. Needle seal 40, needle mount 36 and needleretainer 35 also remain stationary at needle end 15 of barrel 11.

As shown in FIGS. 6 and 7, at the end of plunger 20 depression tocomplete injection of fluid contents of syringe 10, lock 90 is formedbetween lock elements in the form of shoulder 29 of arm 28 of plungerhousing 21 locked onto rim 141 inside release ring 14 of collar 13 atplunger end 12 of barrel 11, to thereby prevent withdrawal of plungerhousing 21 from barrel 11. This also facilitates ease of removal ofcontrol rod 60, which can be manually removed from syringe 10 bybreaking control rod 60 away from plunger member 50 at frangibleconnection 61. Control rod 60 may then be discarded as “clean” waste,leaving syringe 10 with plunger housing 21 and plunger member 50remaining inside barrel 11 for a more compact medical waste disposal.

In light of the foregoing it will be appreciated that the presentinvention provides a relatively simple, robust and inexpensive syringethat is automatically disabled with little or no assistance from theuser to thereby prevent, or at least minimize the likelihood of, re-useof the syringe or needle-stick injury to the user.

Furthermore, the replaceable needle assembly allows a user to select aneedle of appropriate size of gauge or needle length and/or to replace aneedle that becomes bent or burred. Another advantage of the retractablesyringe described herein is that it can accommodate and fullyencapsulate on retraction, needles of varying length up to 1.5 inches(˜3.8 cm) in length, thereby providing great flexibility to the user.

Throughout the specification, the aim has been to describe the preferredembodiments of the invention without limiting the invention to any oneembodiment or specific collection of features. Various changes andmodifications may be made to the embodiments described and illustratedwithout departing from the present invention.

The disclosure of each patent and scientific document, computer programand algorithm referred to in this specification is incorporated byreference in its entirety.

The invention claimed is:
 1. A replaceable needle assembly for aretractable syringe comprising a plunger and a barrel that comprises amounting member, said replaceable needle assembly comprising: a needlemount that is removably mountable to the mounting member of the barrel;a retractable needle including a cannula and a needle body that isremovably mounted to the needle mount, the needle body being engageableby said plunger to facilitate retraction of the retractable needle fromthe needle mount; and a needle retainer that releasably engages saidneedle body of said retractable needle to prevent inadvertent retractionof said retractable needle, the needle retainer flexing to release theneedle body to permit retraction of the retractable needle solely inresponse to a retraction force applied by the plunger when engaged withthe needle body, the retractable needle extending both proximally anddistally from the needle mount and needle retainer prior to retraction.2. The replaceable needle assembly of claim 1, wherein the needle mountcomprises a male member which is receivable by a female member of saidmounting member.
 3. The replaceable needle assembly of claim 2, whereinthe needle mount comprises a screw-thread which in use receives acomplementary screw thread of said mounting member.
 4. The replaceableneedle assembly of claim 1, wherein the needle retainer comprises aplurality of fingers that releasably engage said retractable needle tothereby prevent inadvertent retraction of said retractable needle. 5.The replaceable needle assembly of claim 4, wherein said plurality offingers are releasable from said retractable needle upon retraction ofsaid plunger when engaged with said retractable needle.
 6. Thereplaceable needle assembly of claim 1 wherein the needle body includesat least one shoulder, the needle retainer bearing against the shoulderto retain the retractable needle.
 7. The replaceable needle assembly ofclaim 6 wherein the needle body includes two shoulders, and the needleretainer includes at least two fingers disposed between and bearingagainst at least one of said shoulders to retain the retractable needleand flexing release the needle body to permit retraction of theretractable needle.
 8. The replaceable needle assembly of claim 7wherein the fingers bearing against the at least one of said shouldersretains the retractable needle with an application of a retraction forceup to 6N, the fingers flexing to release the retractable needle withapplication of a force in excess of 6N.
 9. A barrel for a retractablesyringe, said barrel comprising a replaceable needle assembly accordingto claim 1 removably mounted thereto.
 10. The barrel of claim 9, whereinsaid mounting member comprises a female member that receives a malemember of the needle mount of said retractable, replaceable needleassembly.
 11. The barrel of claim 10, wherein the mounting membercomprises a screw-thread which in use receives a complementary screwthread of the needle mount of said replaceable needle assembly.
 12. Thebarrel of claim 9, wherein the barrel further comprises a needle sealcoupled to the mounting member.
 13. The barrel of claim 9, which furthercomprises a collar.
 14. The barrel of claim 13, wherein the collarcomprises a releasing member.
 15. The barrel of claim 13, wherein thecollar comprises one or more lock elements capable of forming a lockwith one or more lock elements of a plunger after retraction.
 16. Aretractable syringe kit comprising: a barrel prefilled with fluidcontents and having a mounting member; a plunger, said plungercomprising: a biasing means; a plunger member releasably connected to acontrol rod; a plunger housing; and a plunger seal mounted to theplunger member; wherein the plunger member, control rod and plungerhousing co-operate to maintain said biasing means in an initiallyenergized state prior to retraction; and a plurality of replaceableneedle assemblies each comprising: a needle mount that is removablymountable to the mounting member of the barrel; a retractable needleincluding a cannula and a needle body that is removably mounted to theneedle mount, the needle body being engageable by said plunger tofacilitate retraction of the retractable needle from the needle mount;and a needle retainer that releasably engages said retractable needle toprevent inadvertent retraction of said retractable needle, the needleretainer flexing to release the needle body to permit retraction of theretractable needle, the retractable needle extending both proximally anddistally from the needle mount and needle retainer prior to retraction.17. The retractable syringe kit of claim 16, wherein the plurality ofneedle assemblies respectively comprise a 0.5 inch needle, a 1.0 inchneedle and a 1.5 inch needle.
 18. The retractable syringe kit of claim16, which comprises a plug removably mounted to the mounting member ofthe barrel.
 19. The retractable syringe kit of claim 16 wherein theneedle body includes at least one shoulder, the needle retainer bearingagainst the shoulder to retain the retractable needle.
 20. A retractablesyringe comprising: a barrel having a mounting member; a plungercomprising: a biasing means; a plunger member releasably connected to acontrol rod; a plunger housing; and a plunger seal mounted to theplunger member wherein the plunger member, control rod and plungerhousing co-operate to maintain said biasing means in an initiallyenergized state prior to retraction; and a replaceable needle assemblymounted to the barrel wherein the needle assembly comprises: a needlemount that is removably mountable to the mounting member of the barrel;a retractable needle including a cannula and a needle body that isremovably mounted to the needle mount, the needle body being engageableby said plunger to facilitate retraction of the retractable needle fromthe needle mount; and a needle retainer that releasably engages saidretractable needle to prevent inadvertent retraction of said retractableneedle, the needle retainer flexing to release the needle body to permitretraction of the retractable needle solely in response to a retractionforce applied by the plunger when engaged with the needle body, theretractable needle extending both proximally and distally from theneedle mount and needle retainer prior to retraction, wherein theretractable needle and the control rod retract relative to the plungerhousing as the biasing means releases energy at a rate controlled by auser acting upon the control rod.
 21. The retractable syringe of claim20, wherein the barrel further comprises a collar.
 22. The retractablesyringe of claim 21, further comprising a lock formed between respectivelock elements of said plunger housing and the collar of said barrel,which lock prevents or hinders removal of the plunger housing from theretractable syringe after retraction of the retractable needle.
 23. Theretractable syringe of claim 20, which is a prefilled retractablesyringe.
 24. The retractable syringe of claim 20 wherein the needle bodyincludes at least one shoulder, the needle retainer bearing against theshoulder to retain the retractable needle.
 25. A method of operating aretractable syringe comprising a barrel and a plunger, including thestep of removably mounting a replaceable needle assembly to the barrel,the replaceable needle assembly comprising: a needle mount that isremovably mounted to the barrel; a retractable needle including acannula and a needle body that is removably mounted to the needle mount,the needle body being engageable by said plunger to facilitateretraction of the retractable needle; and a needle retainer thatreleasably engages said retractable needle to prevent inadvertentretraction of said retractable needle to a barrel of a retractablesyringe prefilled with fluid contents, the needle retainer flexing torelease the needle body to permit retraction of the retractable needlesolely in response to a retraction force applied by the plunger whenengaged with the needle body, the retractable needle extending bothproximally and distally from the needle mount and needle retainer priorto retraction.
 26. The method of claim 25, which includes the step ofremoving a plug from a mounting member of the barrel prior to removablymounting the replaceable needle assembly to the mounting member.
 27. Themethod of claim 25, which includes the step of screw-threadedly mountinga needle mount of the replaceable needle assembly to a mounting memberof the barrel.
 28. The method of claim 25 wherein the needle bodyincludes at least one shoulder, the needle retainer bearing against theshoulder to retain the retractable needle.